Up to five million people per day may use khat, a plant native to East Africa abused for its amphetamine- like effects. In Ethiopia, community surveys found >30% were khat users; studies have reported rates almost double that for persons living with HIV. Focus groups and key informant interviews conducted by Dr. Lifson and colleagues suggest use of khat is a risk factor for default from HIV care, but there no quantitative studies evaluating this association. Ethiopian studies report that only 75% of those started on antiretroviral therapy (ART) are retained in care after one year, with losses greatest i the first six months. Inability to retain HIV patients in care undermines medical and public health benefits of global initiatives to identify HIV patients and enroll them in treatment. This exploratory R21 grant will allow us to evaluate this understudied area among both ART and pre-ART patients who are newly enrolled in care, the groups at highest risk for short-term HIV treatment default. Among HIV-positive persons newly enrolled in HIV medical care, we will: evaluate the prevalence and characterize use of khat and other substances of abuse; analyze demographic, behavioral and clinical factors associated with khat use; evaluate the association between use of khat and retention in HIV care; and identify other factors (including use of other drugs) associated with retention in HIV care 500 HIV-positive adults newly enrolled for medical care will be recruited from two major HIV Clinics in Bahir Dar, and will receive a baseline and 6-month follow-up health survey including: demographic characteristics; khat, alcohol and other drug use; HIV knowledge; quality of life; attitudes about HIV status and internalized stigma; social support; and perceived barriers to medical care. Every 6 months, additional data collected from the HIV Clinic will include body mass index, WHO clinical stage, CD4+ count, and dates of all HIV Clinic visits. Analysis of predictors of current khat use will include demographics, clinial status, and survey responses, with multivariate analyses to identify factors independently associated with khat use. We will also evaluate the correlation between khat and use of other drugs (including alcohol). Retention in HIV care will be defined based upon the fraction of all patients initiating care who continue to be alive and access HIV care according to defined follow-up criteria for ART and pre-ART patients. Our primary hypothesis is that current use of khat is associated with poorer retention in care. Proportional hazards models will be used to estimate associations between covariates and retention, and multivariate models use to identify independent predictors of retention, and to see if there is an association between retention and khat after adjustment for potential confounders. Our plan as a follow-up to this R21 study is to implement and evaluate an intervention to prevent HIV treatment default, including programs to specifically address khat using HIV patients. Data from this study will be used to develop community interventions that contain education, patient support, and motivational counseling. This research will provide us with a solid evidence base on which to build such an intervention.